Control responsive to fluid level



March 17, 1953 w, DILLON 2,631,601

CONTROL RESPONSIVE TO FLUID LEVEL Filed July 29, 1948 2 SHEETS SHEET l .F g 5 16 a? 30 [a 6 56 0 0 50 20 4 1,1 66 2 m dell [f 24210.

March 17, 1953 w. M. DILLON CONTROL.- RESPONSIVE TO FLUID LEVEL 2 SHEETSSHEET 2 Filed July 29, 1948 fzvenfior: Zz/n aeZZ Zf Dalian.

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Patented Mar. 17, 1953 CONTROL RESPONSIVE TO FLUID LEVEL Wendell M. Dillon, Lawrence, Mass, assignor to Watts Regulator Company, Lawrence, Mass, a corporation of Massachusetts Application July 29, 1948, Serial No. 41,314

2 Claims.

The present invention relates to low water cutoff switches, such as employed in connection with a boiler and arranged so as to cut ofi the firing means when the water drops below a predetermined level.

The device includes a float chamber and float for operating a mercury switch.

An object of the invention is the provision of a cutoff switch which is quick acting in cutting off the firing means when the water level drops.

Another object is the provision of a cut-off switch which is retarded in action in connecting the firing means when the water rises to the desired level.

Still another object is the provision of a float operated cut-off switch having respective quick and retarded actions as referred to, in which a differential is set up, stabilizing the action of the float, and causing a positive make and break of the switch.

A further object of the invention is the provision of a novel type of float chamber for a float operated cut-off switch.

A still further object is the provision of a novel means for pivotally supporting the float in a float operated cut-off switch, including means for sealing the mounting. I

Another object is the provision of a novel switch support for actuation by a float in a float operated cut-ofi switch.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my device whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in the accompanying drawings, wherein:

Figure 1 is a Vertical sectional view through the float chamber of the device;

Figure 2 is a view similar to Figure 1, showing the float in a difierent position;

Figure 3 is an enlarged view taken on line 3-3 of Figure 1, showing the switch cover removed;

Figure 4 is a view similar to Figure 3 taken on line 4-4 of Figure 2 on an enlarged scale;

Figure 5 is a top view of the switch mechanism attached to the float chamber;

Figure 6 is a view taken on line 6-6 of Figure 3; and

Figure 7 is a view taken on line 'I-I of Figure 6.

Description Referring in detail to the drawings, the cutoff switch mechanism of the present. invention includes a float chamber I2 which may be formed as a cast piece. The chamber I2 is provided with tapped openings l4 for connection with the boiler with which the device is to be used, at points spaced above and below the normal water level in the boiler. The chamber [2 includes a lower reduced portion l6, and a portion l8 thereabove of greater transverse dimension. The portion l3 includes a bulge 20 flaring out from the wall of the chamber and extending around three sides thereof as may be seen from Figures 1 and 3.

The bulge 20 includes an inclined surface 22 which merges into the wall of the lower portion l6 and an upper inclined portion 24 which merges into the top surface of the chamber. The peak or the widest transverse dimension of the upper portion I8 is therefore spaced intermediate the top of the chamber and the lower portion It.

At one side of the chamber I2 is a laterally flared portion 26 having a vertical flat outer surface. The flared portion 26 is provided with an enlarged opening 28. It may be pointed out that the opening 28 is disposed in the upper portion of the chamber or generally at the same level with the bulge 2b.

The switch mechanism per se is indicated by the numeral 3!! and in'Figures 1 and 2 is shown covered with a protective cover 32. The mounting for the switch mechanism is illustrated in Figures 3 to '7, in which the cover 32 is removed, and includes a plate 34 which fits over the opening 28 in the chamber wall and is secured in place by means of screws 36 or other conventional means. Projections 3? are formed on the plate 34 by means of which the cover 32 is guided and fitted in place; the cover is then held in place by screws tapped into lugs 88. The plate 34 is provided with a reduced central opening 38 (Figures 6 and 7). On each side laterally oi the opening 353 is a projection 40 extending inwardly of the plate 34 or into the interior of the chamber. A float rod 42 is pivoted on a pin 44 which is supported horizontally between the projections 48. The float rod 42 is therefore enabled to swing about the pivot 44 in a vertical plane. The float rod 42 extends through the opening 38 on both sides of the plate 34. The inner end of the float rod 42 is reduced and threaded as indicated at 45 and secured on the reduced portion 45 is a float 48 secured to the float arm 42 in a conventional manner, Surrounding the projections 40 and the float rod 42 is a bellows seal 56, one end of which is hermetically sealed as at 52 to the inner sur- 3 face of the plate 34. The other end of the bellows 52 is sealed to the float rod 42 by means of an adaptor 54 secured to the bellows in a conventional manner.

The mercury switch and switch mounting 30 are mounted on the outer surface of the plate 34. The plate 34 is provided with a plurality of outwardly extending bosses 53 which have interiorly threaded recesses. A plate 60 is disposed in engagement with the bosses 53 with holes aligned with the recesses. Posts 64 having reduced threaded ends are inserted through the holes in the plate and threaded into the recesses; the outer ends of the posts have tapped holes therein. A terminal block 62 is supported on the outer ends of the posts 64, held in place by screws 6i threaded into the holes in the posts. The plate 60 includes a turned over top horizontal flange 66 and side flanges 6B.

A post or pin 10 is secured in the plate 68, as by riveting,' at a point displaced laterally from the plane of vertical swinging of the float rod 42. A horizontal arm l2, having Lip-turned ears M, is pivotally supported on the pin it. The ears M are provided with aligned holes for receiving the pin Ni and the arm is retained on the pin by means of a cotter key.

The arm 12 is in the form of a flat plate and extends transversely across the plane of movement of the float rod 42. The outer or swinging end of the arm 12 is provided with an up-turned ear '16 adjacent the plate 66. Intermediate the ends of the arm 12 is a down-turned lug is extending an appreciable distance below the arm.

An adjusting member 89 is secured to the arm 12 in such a manner as to enable adjustment of the arm with respect to the float rod 32. The adjusting member 80 is in the form of an L, having an upper horizontal leg t2 pivoted at 54 in the ear Hi. The member 86 is provided with an opening 86 at substantially the juncture of the two legs of the member and this opening is adapted to receive the outer extended end of the float rod 42. The adjusting member as also has a downwardly extending leg 83. In the lower end of the lug I8 is an arcuate slot 9% which is curved substantially about the pivot point 8-2 as a center. A screw 92 is inserted through the slot 90 and threaded into the lower end of the leg 8&3. A bracket 94 is secured to the under surface of the arm 12. The bracket 94 has a pair of downwardly extending spring ears 96 between whi h is snapped a mercury switch 93. The mercury switch 98 may be a conventional switch and is supported in the bracket 95 in a conventional manner. The switch 98 also includes terminal wires which are eliminated from the present illustration for purposes of clarity.

The terminal block 62 is provided with a series of terminal connections I for connection of the switch in the circuit for which it is intended.

Use and operation When the level of the water in the boiler drops the level in the chamber also drops, but due to peculiar characteristics of the present invention the rate of drop of the level in the chamber is different from that in the boiler. This characteristic feature will be referred to later in detail.

When the level in the float chamber drops the float lowers and pivots about the pivot pin 44 and the outer end of the float rod d2 swings upwardly. The outer end of the float rod then raises up, and being extended through the opening 85, swings the adjusting member and thereby the arm 12 upwardly about the pivot pin 10. The switch 98 is then tilted tothe position illustrated in Figure 4 wherein it will be noted that the switch is raised out of level position. The switch is then open and the firing means has been cut off.

The screw 92 is turned to clamped position so that the adjusting member 8! and the arm 12 are held in rigid relation with respect to each other, and when the float rod lifts upwardly 0n the adjusting member 30 the arm 12 is thereby raised. For adjusting the relative position of the arm 12 with respect to the float rod the screw 92 is loosened and the adjusting member 86 is swung about its pivot pin 84 to its desired position, the screw being relatively slidable in the siot 9d. The screw is then tightened and a new adjusted position is accomplished between the adjusting member and the arm.

Thus the tilting of the arm 72 and thereby the switch can be varied within a limited range with respect to the float. However, the slot and screw 92 are for the purpose of accomplishing a zero adjustment in an installation to compensate for slight manufacturing inaccuracies in the device.

It will thus be noted that a novel form. of switch mounting as just described has been accomplished in the device of the present inven tion.

The seal accomplished by the bellows 52 is also considered to be novel. The float has freedom of swinging in a vertical plane and the pivot pin 34 of the float rod is positioned intermediate the ends of the bellows so that the bellows is flexed a minimum amount while an effective seal is accomplished.

An important feature of the invention is the bulge or flared portion 25 of the float chamber. In normal operation of a boiler under steaming conditions, the water level in the boiler is not generally steady, but surges rapidly up and down as the steam bubbles break. through the surface of the water. In the case of a uniform dimension float chamber, the surges in the water level in the boiler would be transmitted to the water level in the float chamber, resulting in bouncing of the float with consequent rapid making and breaking of the switch. However, by reason or" the flared feature of the float chamber of the present invention, the surging effect is snubbed in the float chamber. In the case of a rising level of water in the boiler, (i. e., momentary and rapid rising due to surging), there is a certain volume of water displaced into the float chamber, and because of the fact that the volu metric capacity of the float chamber increases per unit vertical dimension as the level rises, the level rises more slowly, because the given volume of water spreads out over a greater area, and therefore does not result in raising the level in the float chamber to the level in the boiler during the short interval of time of the surge; then the momentary surge in the boiler recedes before the level in the float chamber has risen to any appreciable extent. Conversely, on the receding action of the water level in the boiler, the water level in the float chamber drops more rapidly than in a uniform dimension float chamher, and is restored to normal quickly. The water level in the float chamber is therefore held more steady in the surging action of the water U level in the boiler, known in the trade as a nervous water line, but in the case of slow changes of water level in the boiler, the water level in the float chamber corresponds therewith.

Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim as my invention:

1. A fluid level responsive control comprising a float chamber, said chamber having upper and lower openings for connection with a container for fluid, a float mounted in said chamber, said float having a neutral position, said chamber having a bulged-out portion extending around at least three sides of said chamber to provide a level at which the enclosed horizontal cross section area is a maximum, said float being in the neutral position when said chamber is filled with fluid to the level of maximum horizontal cross section area, the change in the level of the fluid within the chamber, per unit volume of fluid entering or leaving the chamber, being a minimum when the chamber is filled with fluid to the level of maximum horizontal cross section area, whereby the float when in the neutral position is located in said bulged-out portion and thereby is least affected by small volumes of fluid entering Or leaving the chamber, said chamber having a substantially uniform portion wherein the horizontal cross section area at difierent levels therein is substantially constant, so that the change of level of the fluid within said uniform portion, per unit volume of fluid entering or leaving the chamber, is substantially constant, said uniform portion extending vertically downward below said level of maximum horizontal cross section area, whereby, as the level of the fluid within the chamber falls, the float enters said substantially uniform portion where the change of level per unit volume of fluid enter- 4 ing or leaving the chamber is substantially uniform.

2. A fluid level responsive control comprising a float chamber, said chamber having upper and lower openings for connection with a container for fluid, a float mounted in said chamber, said float having a neutral position, said chamber having a level at which the enclosed horizontal cross section area is a maximum, the area above and below said level sharply decreasing in value, said float being in the neutral position when said chamber is filled with fluid to said level of maximum horizontal cross section area, the change in the level of the fluid within the chamber, per unit volume of fluid entering or leaving the chamber, being a minimum when the chamber is filled with fluid to the level of maximum horizontal cross section area, whereby the float when in the neutral position is located in the region that is least affected by small volumes of fluid entering or leaving the chamber, said chamber including inclined surfaces on at least three sides of said chamber and extending below and above said level of maximum area, wherein the change of level of the fluid adjacent the inclined surfaces, per unit volume of fluid entering or leaving the chamber, sharply increases from the minimum, said chamber having a substantially uniform portion wherein the horizontal cross section area at different levels therein is substantially constant, so that the change of level of the fluid within said uniform portion, per unit volume of fluid entering or leaving the chamber, is substantially constant, said uniform portion merging into the inclined surface extending below said level of maximum area, said uniform portion extending vertically downward, so that, as the level of the fluid within the chamber falls, the float enters said substantially uniform portion where the change of fluid level per unit volume of fluid entering or leaving the chamber is substantially uniform.

VVENDELL M. DILLON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,492,171 Jennings Apr. 29, 1924 2,043,530 Dezotell June 9, 1936 2,145,199 Kronmiller Jan. 24, 1939 2,178,866 Thomas Nov. 7, 1939 2,204,161 Shepherd June 11, 1940 2,211,440 Shepherd Aug. 13, 1940 2,255,732 Kronmiller Sept. 9, 1941 2,288,223 Bomyer June 30, 1942 

